1. Field of the Invention
The present invention relates to an image recording apparatus for recording images by irradiating a recording material with light beams.
2. Description of the Related Art
In such an image recording apparatus, a recording material is irradiated with light beams emitted from a plurality of optical fibers connected to light sources such as semiconductor lasers, and transmitted through an optical system such as an imaging optical system. At the same time, the optical system and the recording material are moved relative to each other in a primary scanning direction and a secondary scanning direction. In this way, a primary scan and a secondary scan are performed to record an image.
Such an image recording apparatus uses a plurality of optical fibers arranged in rows forming an array. With these rows of optical fibers, luminous points may be arranged at intervals each substantially corresponding to an outside diameter of each optical fiber (i.e. outside diameter of a clad of each optical fiber).
However, the optical fiber has a core diameter defining a light transmitting portion, which is smaller than the clad diameter. Even in a multimode fiber, the core diameter is at most a half of the clad diameter. Consequently, the clad portion of each optical fiber forms a gap on a recording surface to lower the image recording density.
To solve this problem, the formation of gaps between scan lines is prevented by tilting the rows of optical fibers by an appropriate angle relative to the primary scanning direction. In this construction, however, an optical image enlarges with an increase in the number of optical fibers. This results in a disadvantage of having to enlarge optics such as lenses.
An image recording apparatus is proposed in Japanese Patent Publication (Unexamined) No. 2000-141749 to overcome such a disadvantage. This apparatus has N rows of optical fibers supported at a fixed pitch P on a base plate, the optical fiber rows being arranged parallel to a secondary scanning direction. These optical fiber rows are shifted in the secondary scanning direction by 1/N of the pitch P of the optical fibers.
The image recording apparatus described in Publication No. 2000-141749 is fine insofar as enabling a high density image recording without enlarging optics. However, since the optical fibers are arranged at the relatively small pitch P, positioning is far from easy when arranging a plurality of optical fiber rows as shifted by 1/N of the pitch P in the secondary scanning direction. This makes the above apparatus difficult to manufacture.
The object of the present invention, therefore, is to provide an image recording apparatus, easy to manufacture, for enabling a high density image recording without enlarging optics.
The above object is fulfilled, according to the present invention, by an image recording apparatus for recording an image on a recording material by irradiating the recording material with light beams emitted from a plurality of optical fibers, and causing the light beams to make a primary scan and a secondary scan of the recording material, the apparatus comprising a plurality of optical fiber rows each having a plurality of optical fibers supported by a base plate having a plurality of grooves arranged at a fixed pitch P and arranged at said fixed pitch P, the plurality of optical fiber rows being arranged parallel to each other in a direction intersecting a primary scanning direction and a secondary scanning direction, optical fibers disposed at adjacent ends of the plurality of optical fiber rows being shifted from each other by a multiple of the fixed pitch P in a direction of arrangement of the optical fibers, and the optical fibers constituting the plurality of optical fiber rows having projections thereof arranged at a fixed pitch PY in the primary scanning direction.
This image recording apparatus is capable of a high density image recording without enlarging optics. There is no need to arrange the plurality of optical fiber rows as shifted by 1/N of the pitch P in the secondary scanning direction. Thus, the apparatus according to the invention is easy to manufacture.
In a preferred embodiment, the plurality of optical fiber rows are in form of a pair of optical fiber rows arranged at an adjustable angle to the secondary scanning direction. This construction facilitates a positional adjustment between the optical fiber rows.
Preferably, the optical fibers constituting the plurality of optical fiber rows have projections thereof in the secondary scanning direction arranged at a pitch PX of projections in the secondary scanning direction of the optical fibers constituting each of the optical fiber rows. This facilitates control of image recording timing.
The plurality of optical fiber rows may include an equal number of optical fibers, optical fibers disposed at ends of the plurality of optical fiber rows coinciding with each other in the primary scanning direction. This further facilitates control of image recording timing.
In another aspect of the invention, an image recording apparatus is provided for recording an image on a recording material by irradiating the recording material with light beams emitted from a plurality of optical fibers, and causing the light beams to make a primary scan and a secondary scan of the recording material, the apparatus comprising a pair of optical fiber rows each having a plurality of optical fibers supported by a base plate having a plurality of grooves arranged at a fixed pitch P and arranged at said fixed pitch P, the pair of optical fiber rows being arranged parallel to each other in a direction intersecting a primary scanning direction and a secondary scanning direction, the pair of optical fiber rows including an equal number of optical fibers, the pair of optical fiber rows being arranged at an adjustable angle to the secondary scanning direction, optical fibers disposed at adjacent ends of the pair of optical fiber rows being shifted from each other by a multiple of the fixed pitch P in a direction of arrangement of the optical fibers;, and the optical fibers constituting the pair of optical fiber rows having projections thereof arranged at a fixed pitch PY in the primary scanning direction.
In a further aspect of the invention, an image recording apparatus is provided for recording an image on a recording material by irradiating the recording material with light beams emitted from a plurality of optical fibers, and causing the light beams to make a primary scan and a secondary scan of the recording material, the apparatus comprising a pair of optical fiber rows each having a plurality of optical fibers supported by a base plate having a plurality of grooves arranged at a fixed pitch P and arranged at said fixed pitch P, the pair of optical fiber rows being arranged parallel to each other in a direction intersecting a primary scanning direction and a secondary scanning direction, the pair of optical fiber rows being arranged parallel to each other in a direction intersecting a primary scanning direction and a secondary scanning direction, the pair of optical fiber rows including an equal number of optical fibers, the pair of optical fiber rows being arranged at an adjustable angle to the secondary scanning direction, optical fibers disposed at ends of the pair of optical fiber rows coinciding with each other in the primary scanning direction, and the optical fibers constituting the pair of optical fiber rows having projections thereof arranged at a fixed pitch PY in the primary scanning direction.
Other features and advantages of the present invention will be apparent from the following detailed description of the embodiments of the invention.